Think for a second about how much of your life is on your smartphone or tablet. It probably has emails, texts, call logs, contacts, browsing history, social media apps, finance apps, saved passwords, credit card numbers, personal photos and more.

Now think about how easy it would be for a snooping friend or family member to pick up your gadget and poke around in it. Or a thief could easily swipe it from your jacket pocket, your table at a restaurant or your home.

Then there are data-stealing malicious apps and other automated threats hackers like to cook up. And don't forget about advertisers, cellular providers and the government tracking your movements online and in the real world.

In short, there are plenty of risks to the sensitive information on your gadget. That's why you need to take immediate steps to lock down your phone or tablet. Let's look at what settings you need to change and apps you need to install on your Android, Apple or Windows Phone gadget to keep hackers and snoopers at bay.

1. Set a PIN or password

Did you know that one-third of smartphone users don't set up the lock screen on their phones? Many stick with the default "Swipe to unlock" screen, which won't stop a bad guy or even a casual snooper.

You need to use the lock screen that requires a password to continue, and come up with a good number code. This code should be something that isn't easy to guess. Something like 1-2-3-4 or 0-0-0-0 isn't going to cut it.

Apple gadgets make you set up a passcode for the lock screen the first time you use them. However, if you created it a while ago, it might be time to beef it up. Go to Settings>>Passcode to edit your passcode and then click here to make a more secure passcode for iOS.

For Windows phones, go to the Start screen and tap Settings>>Lock screen to set up your passcode.

Important: In the lock screen area, be sure you set your gadget to lock automatically after a few minutes of inactivity. If you have it set to an hour and a thief or snooper swipes it, they'll have plenty of time to poke through your information or install a spy app.

2. Only install trusted apps

Bad apps are loaded with malware that can infect your gadget with viruses and steal your information. Newer ones even hijack your contact list to spam your friends and infect their gadgets.

You can lower the risk by only installing apps from the major app stores: Google Play, Amazon Appstore, Apple iTunes and Microsoft's Windows Store. Third-party app stores often host malicious apps, usually disguised as popular real apps.

Actually, this isn't such a big problem for Apple and Microsoft users because they're locked into their own app stores. However, Android gadgets allow you to visit app stores besides Google Play, although this feature is turned off by default in Amazon gadgets. Click here to learn the signs of an infected Android gadget.

To make sure you don't accidentally install "untrusted" Android apps, go to Settings>>Security and uncheck the "Unknown Sources" option. You should also check the "Verify Apps" option if you have it.

Even legitimate apps can grab information from your phone that you might not want to share. That's why you need to check the app's permissions before you install it.

Does it make sense for it to grab your GPS location or get access to your gadget's camera? Think twice about installing an app that wants free rein over your gadget, especially if it really doesn't need it. Visit a site like PrivacyGrade to find out why an app needs certain permissions.

Also, read each app's privacy policy. Find out what information it collects and what it does with that information.

3. Stop advertisers and more from tracking you

It's no secret that advertisers are tracking where you go online and your cellular provider is helping them. In fact, some providers, like Verizon, are doing it in a way that exposes you to hackers as well.

4. Enable remote location and wiping

One nice thing about smartphones and tablets is that they're portable so you can easily take them anywhere. The downside is that you can easily lose them or a thief can walk off with them in a heartbeat.

The good news is that smartphone theft is down thanks to the growing amount of "kill switches" that make it harder to wipe and resell them. In 2013, 3.1 million Americans have had their smartphones stolen while it was only 2.1 million in 2014, and probably less in 2015. Still, any number in the millions is a lot and that doesn't include the 3.1 million phones in 2014 (and likely similar in 2015) that were simply lost.

If your gadget is lost or stolen, tracking apps can tell you exactly where your phone is. These apps also let you wipe sensitive information remotely. If your phone does end up in the wrong hands, you can at least make sure somebody else doesn't get your information.

6. Wipe your old gadget before donating, selling or recycling

Upgrading to a new phone or tablet and ditching your old one? Make sure to wipe your old phone before you sell or recycle it. You definitely don't want the information on your phone getting into the wrong hands.

I don't just mean deleting apps, files, photos and videos. Hackers and other criminals can easily recover deleted information. I mean wiping the phone's internal memory so that no trace of personal information is left behind.